Soon after entering World War Two, the U.S. launched Boeing B-17 “Flying Fortresses” and Consolidated B-24 “Liberators” from bases in England’s eastern countryside. Americans bombed their targets during the day and the British at night. The B-17 was manned by a crew of 10 and bristled with machine guns. Up to 1,000 of these heavy bombers would fly in a 3-dimensional formation in which boxes of aircraft were stacked one above the other to take full advantage of their combined defensive firepower. But losses were severe and it was only after the arrival of long-range fighter aircraft capable of escorting the bombers to and from their targets that losses dropped to acceptable levels. Watch “Mighty Eighth Air Force B-17s in Combat Action” below. Image and story courtesy of “Life and Death Aboard a B-17, 1944,” EyeWitness to History (2005).